MERCURY REMOVAL UNIT
With the rising demand of processing natural gas, mercury is a common problem in Oil and Gas Processing Fields. In the case of natural gas, it is present in its elemental form but in case of condensates and crude oil it may also be present as organo-metallic and ionic compounds. The primary reason for removing mercury from natural gas is to protect aluminum heat exchangers from failure due to liquid metal embrittlement or amalgam corrosion. These heat exchangers are used in cryogenic hydrocarbon recovery plants and in natural gas liquefaction plants.
The other issues with presence of mercury in gas streams are:
- Exposure of personnel to mercury during maintenance operations
- Difficulty in disposal of mercury contaminated equipment
- Emissions to the environment from burning of mercury-containing gas
The most basic process system design is a single vessel with a non-regenerable mercury adsorbent. The mercury guard bed is designed with a bypass to allow replacement of adsorbent without interruption of gas flow. Where even temporary bypassing of the guard bed is not acceptable, a lead/lag dual-vessel configuration is provided. This facilitates continuous operation by allowing replacement of the spent media while the system remains online. Two vessels operating in parallel are used where pressure drop is a critical process parameter.